Date of Publication

Spring 4-24-2015

Document Type

Undergraduate Project

First Supervisor

Edward Freeman PhD.

Department

Biology

Abstract

Oxytocin (OXT) is a neuropeptide synthesized in the hypothalamus and stored in the posterior pituitary gland. Its most known functions include being involved in the stimulation of the uterus during childbirth and allowing for milk letdown in the process of lactation after birth. OXT has also been implicated to play a role in parental care and sex behavior. Specific binding to brain oxytocin receptors (OXTR) was observed by in vitro receptor autoradiography with an iodinated OXT analogue in the monogamous prairie vole (Microtus ochrogaster) and the polygamous montane vole (Microtus montanus). What was found was that OXTR density in the prairie vole was highest in the prelimbic cortex, bed nucleus of the stria terminalis, nucleus accumbens, midline nucleus of the thalamus, and the lateral amygdala. In contrast, OXTR density in the montane vole was highest in the lateral septum, ventromedial nucleus of the hypothalamus, and cortical nucleus of the amygdala. Prairie voles show a high level of parental care in both naïve and postpartum individuals, whereas montane voles show a much higher level of parental care postpartum. Differences in OXTR distribution were also seen in two additional species of voles, the monogamous pine vole (Microtus pinetorum) and the polygamous meadow vole (Microtus pennsylvanicus). The receptor distribution of two other neurotransmitter systems that play a role in the mediation of social behavior (benzodiazepines and µ opioids) were also studied but showed little comparable differences between monogamous and polygamous species, which further highlights the importance of OXTR distribution as a mediator of social behavior.

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